Radiosonde antenna system



Jan. 2, 1945. c, PEAR, JR 2,366,423

RADIOSONDE ANTENNA SYSTEM Filed Aug. 17, 1942 Char/es B. PearJ Patented Jan. 2, 1945 2,366,423 KADIOSONDE ANTENNA SYSTEM Charles B. Pear, Jr., Prince Georges County, Md.,,

assignor to Washington Institute of Technology, Inc.. Washington, D. C., a corporation of Delaware Application August 17, 1942, Serial No. 455,110

6 Claims.

This invention relates to the art of radiosonding, by which is meant the radiation, from a transmitter carried aloft by a balloon, of signals which are caused to vary in accordance with changes in atmospheric conditions such as humidity, temperature and pressure, the reception of such signals on the ground and the interpretation of such signals to record changes in at mospheric conditions at various altitudes.

In order to allow ascension of the transmittercarrying balloon to as great a height as possible, it is necessary that the transmitting apparatus, including the power supply, be small and light, thus limiting the amount of energy available for radiation. It has also been found that in reaching its maximum altitude of approximately kilometers the radiosonde will often travel as much as 150 kilometers laterally from the starting point and, therefore, from the point at which the radiated signals are received. It will be apparent that the combination of low permissible power, because of weight considerations, with large possible distance over which transmission must be effected, places a considerable burden on the transmitting apparatus and often results in the reception of signals which are too weak for proper interpretation.

It is accordingly the principal object, of this invention to provide means for increasing the effective signal strength of a radiosonde transmitter without materially increasing the load which must be supported by the balloon.

A further object is to provide means to concentrate the energy radiated by a radiosonde transmitter in such a way that, at the most distant lateral point which the transmitter will reach, the signal strength at the receiver or starting point will be a maximum, while increased signal strength will be achieved for lateral travel of the radiosonde less than the maximum.

Other objects and features of novelty of the invention will be made apparent by the following description and the annexed drawing which, it will be understood, is only illustrative of the invention and imposes n limitation thereon not imposed by the appended claims.

Referring to the drawing, in which similar reference numerals and letters refer to like parts,

Fig. 1 is a view of a radiosonde apparatus embodying means according to this invention;

Fig. 2 is a plan view taken on line 2-2 of Fig. 1, and

-Fig 3 is a diagram showing the fields radiated out the use of means according to this invention.

By this invention I provide means for concen trating the'energy radiatedby the radiosonde transmitting apparatus in such a mannerthat the signal strength increases from a minimum in a direction substantially vertically downward from the antenna to a maximum in a plane ex, tending substantially horizontally through the upper end of the antenna, whereby as the radiosonde drifts laterally from the point where the signals are received the strength of the received signals will not decrease.

In putting my invention into effect I provide a single antenna l0 depending from the transmitter case 8 and above this antenna I provide a horizontal reflector l2 which concentrates the radiations from the antenna ID in the manner required to prevent decrease in signal strength at the point of reception as the radiosonde ascends and drifts laterally from the point where the signals are received. In its preferred form, which is illustrated in Figs. 1 and 2, the reflector comprises a plurality, for example eight, of radial, metal wires or rods l4 connected together at their inner ends and supported there by the case 8 and, at their outer ends supported by a hoop I6. Support for the hoop may be provided by strings or wires l8 which are attached at their outer ends to the hoop and at their inner ends to the upper part of the case 8 or to the string 6 which connects the case to the balloon. In a preferred form the reflector may be six wavelengths in diameter but if special results or effects are desired other diameters must be determined experimentally.

In Fig. 3 of the drawing, the dotted line figure A represents the vertical field pattern for a simple di-pole comprising two quarter-wave vertical radiators supported respectively above and below the transmitter case and not having associated therewith any means according to this invention, and therefore representing the vertical field pattern produced by prior art radiosondes. The full line figure B represents the vertical field pattern for a 0.625 wave antenna supported beneath a reflector in the manner taught by this invention. It will be seen that the two fields are of substantially equal strength along a vertical line extending downwardly from the antenna while the field B is of considerably greater strength than field A along substantially all lines through the antenna and inclined below the horizontal. Further, it will be seen that the strength of field B along such downwardly inclined lines is considerably greater than the strength of the same field along the downwardly-extending vertical line.

By reason of these relative strengths of the field B in difierent directions downward from the transmitter it will be seen that if the balloon raises the radiating means vertically upwardly from the starting point without lateral drift, the signal strength at the starting point will be a minimum but will always be suficient for proper reception inasmuch as in this case the distance of the transmitter from the receiving point will also be a minimum. The radiated signal will increase in the direction of the receiver with lateral drift of the-balloon and transmitting means during ascent; as will be seen from a consideration of diagram B. There will, therefore, be no decrease in received signal strength due to lateral drift, as the radiated signal will increase with increase in the lateral distance of theradiating means from the receiver. At a height of 20 kilometers and a lateral distance of 150 kilometers from the starting point the radiated signal strength will be represented by the point at which a line through the antenna 8 below the horizontal intersectsthe diagram B, as shown in Fig. 3. The reflector will substantially prevent radiation above the plane thereof; this being indicated in Fig. 3 by lack ofrepresentation of field B above the horizontal line through the reflector.

While I- have described and illustrated one embodiment of my invention it will be apparent to those skilled in the art that other'embodiments thereof and modifications of the disclosed structure may be made without departing in any way from the spirit or scope of the invention, for the limits of which reference must be had to the appended claims.

What is claimed is:

1. A system of determining meterological conditions by radio, comprising an aerial body adapted to freely float in space, a radio transmitter carried by the aerial body, a normally vertical antenna carried by the aerial body, having an effective radiating portion extending below the transmitter only, and connected and adapted to radiate signals supplied thereto by the transmitter, and means carried by the aerial body for radiating signals from the antenna having minimum strength in a substantially vertical direction below the aerial body and maximum strength in a substantially horizontal plane through the approximate location of the aerial body as it floats in space, said means comprising a reflector positioned entirely above the antenna.

2. A system according to claim 1, in which said means comprise a substantially horizontallydisposed reflector above the antenna.

3. A system according to claim 1, in which said means comprise a plurality of substantially horizontal conducting members extending radially outward from a point adjacent the upper end of the antenna.

4. A system according to claim 1, in which said means comprise a plurality of substantially horizontal conducting members extending radially outward from a point adjacent the upper end of the antenna and having their outer ends connected and supported by a circular hoop.

5. A system according to claim 1, wherein the antenna is 0.625 wavelength.

6. A system according to claim 1, wherein the reflector is six wavelengths in diameter.

CHARLES B. PEAR, JR. 

